Fire control system

ABSTRACT

This invention is an assembly for automatically controlling the fire size of an oil burner, the fire size being regulated in response to the signal of boiler steam pressure over a wide pressure range. The signal is transmitted through a steam pressure gauge line and an electronic pulsor to a driving motor, which actuates the present assembly. This assembly includes a shaft driven by a motor, on which shaft valve control members are mounted for regulating the amount of oil and an atomizing agent which are mixed together to control the fire size in a range from low fire to high fire. Each valve control member includes an adjustable camming surface, selected portions of which are in contiguous engagement with a floating cam roller which actuates a valve plunger for controlling the opening and closing of each valve through which oil and the atomizing agent pass.

United States Patent I 91 Devoe [73] Assignee: Frank Ray Neal, Jr., Manassas, Va.

; a part interest 22 Filed: Dec. 28, 1970 21 Appl.No.: 101,995

[75 Inventor:

[52] U.S. Cl. ..236/26 E, 74/568, 251/255,

236/78 [51] Int. Cl. ..F22b 35/06 [58] Field of Search ..25l/25l, 255, 258;

236/78 C, 12 A, 14, 26 E, 26 A; 74/55, 568 R Primary Examiner-William E. Wavner Att0meyShlesinger, Arkwright & Garvey 57 ABSTRACT This invention is an assembly for automatically controlling the fire size of an oil burner, the fire size being regulated in response to the signal of boiler steam pressure over awide pressure range. The signal is transmitted through a steam pressure gauge line and an electronic pulsor to a driving motor, which actuates the present assembly. This assembly includes a shaft driven by a motor, on which shaft valve control members are mounted for regulating the amount of oil and an atomizing agent which are mixed together to control the fire size in a range from low fire to high fire. Each valve control member includes an adjustable camming surface, selected portions of which are in contiguous engagement with a floating cam roller which actuates a valve plunger for controlling the opening and closing of each v lve through which oil and the atomizing agent pass. I

10 Claims, 2 Drawing Figures PATENTEDAPR1 0 I973 SHEET 1 OF 2 INVENTOI A lberf W. Devog ATTOINKYS FIRE CONTROL SYSTEM BACKGROUND AND OBJECTS In oil burners which are used principally for commercial applications, it is required that the size of the fire be varied in accordance with the boiler steam pressure. This is conventionally effected at the present time by adjusting the quantity of oil and an atomizing agent, such as steam or air, which are intermixed to produce the desired fire size. These variations in the quantity of the oil and the atomizing agent have been controlled manually in the past, but more recently, means have been provided for automatically changing the quantity of oil and steam or air which are intermixed in response to variations in the boiler steam pressure. This is done by means of an electronic pulsor which actuates a driving motor to selectively rotate the drive shaft of the motor in either direction in response to variations in steam pressure. The rotation of the drive shaft actuates valves, such as Atlas valves to the burner. It has been found, however, that these valves are of limited value since they do not accurately match the oil and steam or air flow from one adjustment to the other, and do not possess the range of incremental adjustments cor responding to the range of the variations in steam pressure. Consequently, a possible air polution situation is created and the adjustments of the oil and steam'or air flow in response to variations in boiler steam pressure are not accurate.

It is an object of the present invention to provide a fire control assembly for automatically and accurately regulating the relative quantities of oil and an atomizing agent which pass through a valve to a burner, the particular amounts of each ingredient being synchronously intermingled in response to fluctuations in the boiler steam pressure, for producing a fire which is automatically adjusted in small increments from low fire size to high fire size.

Another object is to provide an assembly of the character described for accurately homogenizing the fuel and atomizing agent mixture in order to provide 100 percent combustion throughout the range of adjustment of the assembly, thereby eliminating the threat of air pollution caused by incomplete combustion.

Another object is to provide an assembly of the character described for controlling and regulating the fire size of a burner by adjustment of the oil and steam or air valves by automatic operation of an adjustable camming member, various parts of the camming member being selectively engaged with the valves for controlling the flow of oil and steam or airto the burner.

Other objects are to provide a camming member including a cam drum of cylindrical shape having adjustable screw members through the periphery thereof extending through an arc of at least 180, the screws being adjusted to effect engagement with a floating cam follower which is slidably adjustable under urging of the screw member to effect gradual closing or opening of the valve upon movement of the cam member through an arc of 180.

A still further object is to provide an assembly of the character described which effects a gradual, uniform and synchronous adjustment of the oil and atomizing agent valves controlling the flow of fuel to a burner, the

assembly at all times maintaining the same proportion between the oil and atomizing agent mixture in order to insure complete combustion.

Other objects will be apparent from the following description of the presently preferred form of the present invention, taken in conjunction with the appended drawings.

DESCRIPTION OF THE FIGURES OF THE DRAWINGS FIG. 1 is a front elevational view of the present invention, portions thereof being shown in section to dis close details of construction, and

FIG. 2 is a side elevational view of the present invention, portions thereof being shown in section to disclose details of construction.

DESCRIPTION OF THE INVENTION In FIGS. 1 and 2, there is illustrated a boxlike structure 20, within which is mounted a supporting panel 22 fixed to a back panel of the boxlike structure by suitable means 24.

The assembly of the present invention is illustrated for use with a Barber Colman control set manufactured by Hadlock Company of South Freeport, Maine, although it may also be employed with other suitable control means. In the drawings, there is shown a control box containing an electronic pulsor 28 for actuating a motor 30 in response to fluctuations in boiler steam pressure such as, for example, over a 10 to 60 psig range. Motor 30 is of the reversing and proportioning type, having a 180 angular motion of the drive shaft 34 in a timing of seconds for travel of the motion.

Drive shaft 34 is joined by a coupling assembly 36 to a jackshaft 38 which is supported by spaced bearing brackets 40 and 41 connected to supporting panel 22. A pair of like valve control members 42 and 44 are fixedly mounted on jackshaft 38 for regulating flow through an oil valve 46 and a valve 48 through which an atomizing agent such as steam or air passes.

Valve control members 42 and 44 are of like construction, each including a cam drum 50 centrally mounted on jackshaft 38. Cam drum 50 is provided with a circular flange 52 adjacent the periphery of jackshaft 38, a screw 54 extending through the flange into engagement with a keyway 56 of the jackshaft for fixing the cam drum thereto. A locknut is indicated at 58.

The outer periphery of each drum 50 is further provided with an outer flange 60 in spaced relation to jackshaft 38, which extends through an angle of at least [80 of the cam drum periphery. Adjustable screws 62 are threaded through flange 60 and are substantially coextensive therewith, the screws being fixed in the selected position of adjustment by locknuts 64. The screws may be arranged on the flange in pairs, as shown, or in a single row, if desired.

As shown to advantage in FIG. 2, the rim of flange 60 is provided with indicia 66, which preferably take the form of consecutive numbers representing the increments of adjustment of each valve to be effected by the camming action of each valve control member.

Each valve control member 42 and 44 further includes a cam roller 68 of cylindrical shape, the roller being provided with a vertical slot 70 extending longitudinally through the roller, through which jackshaft 38 extends. As shown in FIG. 2, jackshaft 38 is concentric with cam drum 50, while vertically adjustable cam roller 68 may assume various positions of adjustment which are either concentric or eccentric with respect to cam drum 50. It will further be obvious from a consideration of FIG. 2 that movement of cam roller 68 in a vertical direction is carried out by virtue of the positioning of jackshaft 38 in slot 70 coupled with the engagement of the periphery of cam roller 68 with adjustment screws 62, the particular location of jackshaft 38 in the slot being determined by the degree of extension of adjustment screws 62 internally of the cam drum. The screws are adjusted in a manner to be hereinafter more fully described for producing a camming efiect for carrying out the objects of the present invention.

Each valve control member further includes a follower plate 72 which is centrally mounted on jackshaft 38 in adjacent, spaced relationship to cam drum 50. Securement of plate 72 to the jackshaft is effected by means of a collar 74 having an adjustment screw 76 extending through the collar into locking engagement with a keyway 78 of jackshaft 38. A locknut is indicated at 80. A cam follower 82 pends from the lower extremity of cam roller 68, a face of the cam follower engaging a face of follower plate 72. The lower terminal of cam follower 82 is secured to a thrust block 84 by suitable means 86, which thrust block is in operative engagement with valve 46 or 48.

Valves 46 and 48 are of like construction, each of which includes a V-port 88 forming a part of the Barber Colman control set, and connected with an inlet pipe 90 and an outlet pipe 92, the valve being mounted on a stationary valve bracket 94 secured to panel 22. V alves 46 and 48 are of conventional construction and each includes a valve plunger 96, the upper end of which is fixedly engaged with, and movable vertically in response to the movement of, thrust block 82. Valve plunger 96 is provided with spaced collars 98 and 100 which are fixed to the valve plunger, between which is a convolute spring 102 for normally biasing each valve to a closed position. In this way, upon downward movement of thrust block 84 in response to a corresponding movement of cam follower 82, produced by the engagement of the adjusting screws of cam drum 50 with cam roller 68, each of valves 46 and 48 are open to an extent controlled by the camming action of adjustment screws 62 on cam roller 68. I

In FIG. 1 there is illustrated an index arrow 104 which is fixed to hearing bracket 41, the index arrow of the fire control assembly, thereby also indicating the fire size of the burner. A shaft collar is indicated at 108.

In order to operate the fire control assembly of the present invention, there is provided a control panel 110 also forming a part of the Barber Colman control set, having an off-on switch 112 and a selector switch 114. A dial is indicated at 116. The dial is marked with indicia to which the switch may be turned for controlling the activity of motor 30, the dial providing two stop positions, and an open position which will drive the motor to high fire position, a closed position which will drive the motor to low fire position and an auto position which will release the motor to the command of automatic controls.

Before the assembly of the present invention is ready for use, it must be calibrated by adjusting the cam members 62 to produce incremental changes in the movement of the cam roller and valve plunger in a gradual, uniform manner in response to variations in the signal of boiler steam pressure. It has been found that best results are obtained by using 15 pairs of cam members arranged along the periphery of the cam drum, each cam member being adjusted to a pre-set position to form an internal cam shape, eccentric to the shaft, and of adjustable shape and rise so that the tips of the screw members contact the cam roller to impart a reciprocating motion to the cam follower and the valve plunger.

To efiect this adjustment, shaft 38 is positioned so that it is in position 0 as indicated by index arrow 104 on the follower plate of control member 44. In this position the number 3 cam member, as indicated by the indicia 66 on flange 60 will be directly under the center of jackshaft 38 and cam roller 68. The hand valve (not shown) for the steam is turned on and the number 3 cam member is screwed to about three turns inside the cam drum inner diameter. The lift (1' the steam valve is adjusted until a moderate flow of steam is passing in to the burner barrel, following which the nuts on the two valve stems are tightened above and below the spring.

The burner ignition system and the oil hand valve are turned on with a screw driver, following which the stem of the oil valve is pried up until the burner fires. This is used as the trial low fire position. The number 3 screw of the oil cam drum is turned three turns beyond the inner diameter of the cam drum rim. Holding the oil valve in the low fire position, the valve stem and valve plunger threads are adjusted until the cam roller and follower are in contact with the number 3 screw and the mechanism will hold the valve open in the low fire position.

The valve stems of the steam valves are adjusted up or down to provide a proper oil-steam ratio of the low fire. Wood wedges are inserted on top of the valve guide bracket 94 and the underside of the blade of cam follower 82, to maintain the low fire position. All the cam members are backed out to the three turn position i of the number 3 screws, on both the steam and oil cams. In this setting, the fire will stay in the low fire position throughout the 1 travel of the cams.

The clamp screw on the motor shaft half of the drive coupling 40 is then loosened and, with the wood wedges in place, the shaft and drums are rotated upwardly on the front side until the number 27 cam member is at the bottom, under the cam roller and follower. Holding the drums in place, the power switch 112 isturned on and selector switch 114 is placed at the open position. The motor is then allowed to run to the full open travel position and the motor half of the drive coupling is locked to the drive shaft. Power switch 112 is next turned off. Locknuts 64 of the two number 3 cam screws are then tightened to the lock position. The number 27 cam members of both the oil and steam cams are then advanced together, all the while maintaining a fire, counting the number of turns from the three turn starting position, until high fire is reached. At this high fire position, the steam rate is proper for peak fire efficiency. Locknuts 6 3 on the number 27 cam screws are then locked on both drums.

The number of added turns made on each of the number 27 drum screws is then recorded to obtain the highest fire setting. For example, if there are eight turns on the oil drum cam member and it on the steam drum cam member and these screws have a 24 pitch thread, this means that three turns advances the cam member by one-eighth inch. Now in the situation where there were eight turns of advance of the oil drum cam member from low fire to high fire position, the eight turns must be divided into 24 increments along the progression from the number 3 to the number 27 earn members. Therefore, eight divided by 24 is one-third of a turn for each screw as the cam advances. Therefore, screw number 6 is set up one turn, number 9 two turns, number 12 three turns, etc. to number 24. Number 4 is then set at one and one third turns, number 5 at one and two thirds, number 7 at two and one third, number 8 at two and two thirds turns, etc. This provides a uniform rise rate of the oil drum cam group.

In the case of the steam drum, there are ten turns to divide up between 24 positions, which works out to five-eighths of a turn per interval. Number 8 screw is set in two turns, number 13 fourtums, number 18 six turns, and number 23 eight turns. The intermediate screws are adjusted proportionately. In this manner, as close a trial setting as possible is obtained by calculation.

Next, power switch 112 is turned on and selector 116 is turned to the closed position. The system is then run down to the number 23 screw position. The steam rate is adjusted for a good mixture, and then the screws are adjusted down the scale until all cam screws are set properly and locked. Set screws 1 and 2 are set on both drums the same as number 3, following which they are locked. Screws number 28 and 29 are then set the same as number 27 on both drums and locked.

At low fire position, a lightoff is tried to be sure the firing is dependable, following which the control selector switch is set at auto. The system is then ranged over the full range from low to high fire, noting any areas where fire propagation is inferior so that these areas can be improved visually before instrumentation is employed. In case of inferior areas, the steam rate is adjusted to good flame appearance. After the above procedure has been carried out, combustion analyzing instruments may be employed, starting with the low fir ing rate and the steam cam screws are adjusted at each of the points from numbers 3 to 27 for proper combustion analysis condition.

OPERATION In use of the fire control assembly of the present invention, selector switch 114 may, if desired, be manually set for the open position for high fire, and to the close position for a low fire.

When it is desired to have the present assembly automatically respond to variations in the steam pressure of the boiler, the selector switch is moved to the auto position. When in this position, motor '30 is automatically actuated by electronic pulsor 26 to rotate the jackshaft 38 to the extent indicated by the pulsor and thereby change the location of cam roller follower arm 82 and valve plunger 96 by virtue of the movement of a different set of cam screws 62 into engagement with the cam roller. This procedure is repeated in response to the pressure condition of the boiler, control members 42 and 44 responding to fluctuations in boiler steam pressure to admit the proper mixture of steam and oil to the bumer for effecting complete combustion. In this manner, a proper size and quality of fire is produced to satisfy the demands of the steam pressure signal. Provision is also made to receive an external signal from a combustion monitoring system and, upon release by the external flame control device, the present system will respond to the steam pressure signal and take control of the tire size to maintain the proper preset oil and steam atomizing rates at the burner.

With the assembly of the present invention, an automatic system is provided for maintaining the size and quality of the burner fire in a manner to insure complete combustion and to prevent pollution of the atmosphere, while at the same time permitting manual operation thereof in the event that it is desired to manually control the fire size. The assembly of the present invention is responsive to actuation of a reversing and proportioning motor to positively insure that the steam or air and oil is intermixed in the correct proportion in all ranges of the fire from low to high size. Additionally, by providing a camming surface extending through at least I", means is provided for effecting small increments of change of the fire in response to pressure changes, thereby affording a very gradual, uniform change in the amounts of steam or air and oil which are admitted through their respective valves for intermixture and feeding to the fuel burner.

While the assembly of the present invention is shown and described as embodying two valve control members, it is to be understood that such has been done for purposes of illustration only, and that any number of valve control members may be employed, depending on the particular system in which it is employed. Various other changes may be made within the scope of the appended claims.

What I claim is:

l. A fire control assembly for regulating the flow of fuel and an atomizing agent through valves to a burner, the assembly comprising:

a. a rotatable shaft, Y

b. power means for rotating said, shaft,

c. means for actuating said power means,

d. a valve control member fixedly mounted on said shaft and rotatable therewith, said valve control member including a cam drum mounted on, and movable with, said rotatable shaft,

f. camming members extending through the periphery of said cam drum to a predetermined extent, to provide a camming surface interiorly of the cam drum formed by the inner limits of said camming members, and

. means engaged with said camming surface and in operative engagement with the valve,

. said means engageable with said camming surface being movable in a direction to open and close the valve for regulating the flow of fuel through the valve upon rotation of said shaft.

2. The tire control assembly of claim 1, wherein said camming members comprise a. screw member adjustably threaded through said cam drum periphery,

b. said screw members being arranged along a substantial portion of said cam drum periphery.

3. The fire control assembly of claim 2, wherein a. said screw members extend through an arc of at least 180 of the cam drum periphery.

4. A fire control assembly for regulating the flow of fuel through a valve to a burner, in response to boiler steam pressure, including a. a rotatable shaft,

b. power means for rotating said shaft in either direction,

c. a valve control member fixedly mounted on said shaft and movable therewith,

d. said valve control member including a cam drum fixedly mounted on said shaft,

e. a plurality of screw members arranged in a row along a substantial portion of the periphery of said cam drum,

f. said screw members extending through the cam drum periphery to varying extents, whereby the inner ends of the screw members form a camming surface,

g. said valve control member further including a cam roller,

h. said cam roller being provided with an elongated vertical slot through which said shaft extends,

i. the periphery of said cam roller being in selective engagement with a portion of the camming surface of said cam drum,

j. a cam follower pending from said cam roller into actuating engagement with the valve, and

k. means for automatically energizing said power means in response to variations in boiler steam pressure to rotate said shaft in either direction,

1. whereby the point of contact of said camming roller is changed, thereby effecting vertical movement of said cam roller and cam follower to change the rate of flow of fuel through the valve.

5. A fire control assembly for regulating the flow of I fuel and an atomizing agent through valves to a burner, the assembly including:

a. a rotatable shaft,

b. power means for rotating said shaft,

c. means for actuating said power means,

d. a pair of like valve. caitrol members fixedly mounted on said rotatable shaft,

e. each of said valve control members including cam members providing a camming surface fixedly mounted on said rotatable shaft,

f. means engageable with said camming surface of each control member in operative engagement with the valves for regulating the flow of fuel and atomizing agent through the valve,

g. said means engageable with each of said camming surfaces including a cam roller,

h. said cam roller having a vertical elongated slot through which said rotatable shaft extends, said cam roller being in selective engagement with portions of said cam members upon rotation of said shaft,

j. whereby the valves are opened and closed.

6. The fire control assembly of claim 5, wherein a. said cam member includes a cam drum fixedly mounted on said rotatable shaft b. a plurality of camming members extending through the periphery of said cam drum a predetermined extent c. the inner ends of said camming members forming a camming surface,

(1. said camming surface being in engagement with said cam roller.

7. The fire control assembly of claim 6, wherein a. said camming members comprise screws threaded through said cam drum and adjustable with respect thereto.

8. The fire control assembly of claim 7, wherein a. said camming members extend through an arc of at least on said cam drum surface.

9. A fire control assembly for regulating the flow of fuel and an atomizing agent through valves to a burner the assembly including a. a rotatable shaft,

b. power means for rotating said shaft,

c. a pair of synchronously operating valve control members mounted on said shaft, and movable therewith,

d. each of said valve control members including a cam drum fixedly mounted on said shaft,

' e. a plurality of screw members arranged in a row along a substantial portion of the periphery of said cam drum,

f. said screw members exending through the cam drum periphery to varying extents, whereby the inner ends of the screw members form a camming surface,

g. each of said valve control members further including a cam roller,

h. said cam roller being provided with an elongated vertical slot through which said shaft extends,

i. the periphery of said cam roller being in selective engagement with a portion of the camming surface of said cam drum,

j. a cam follower pending from said cam roller into actuating engagement with the valve, and

k. means for automatically energizing said power means in. response to variations in boiler steam pressure to rotate said in either direction,

1. whereby the point of contact of said camming surface of each valve control member with the cam roller is changed, thereby effecting vertical movement of said cam roller and cam follower to change the rate of flow of fuel through the valve.

10. A fire control assembly for regulating the flow of fuel and an atomizing agent through valves to a burner, the assembly including:

e.- said rotatable valve control member including means providing a camming surface, and

f. means between said camming surface and one of the valves for opening and closing the valve for regulating the flow through the valve upon rotation of said shaft,

g. said means between said camming surfaceand valve including a cam roller, h. a cam follower pending from said cam roller into actuating engagement with the valve. 

1. A fire control assembly for regulating the flow of fuel and an atomizing agent through valves to a burner, the assembly comprising: a. a rotatable shaft, b. power means for rotating said shaft, c. means for actuating said power means, d. a valve control member fixedly mounted on said shaft and rotatable therewith, e. said valve control member including a cam drum mounted on, and movable with, said rotatable shaft, f. camming members extending through the periphery of said cam drum to a predetermined extent, to provide a camming surface interiorly of the cam drum formed by the inner limits of said camming members, and g. means engaged with said camming surface and in operative engagement with the valve, h. said means engageable with said camming surface being movable in a direction to open and close the valve for regulating the flow of fuel through the valve upon rotation of said shaft.
 2. The fire control assembly of claim 1, wherein said camming members comprise a. screw member adjustably threaded through said cam drum periphery, b. said screw members being arranged along a substantial portion of said cam drum periphery.
 3. The fire control assembly of claim 2, wherein a. said screw members extend through an arc of at least 180* of the cam drum periphery.
 4. A fire control assembly for regulating the flow of fuel through a valve to a burner, in response to boiler steam pressure, including a. a rotatable shaft, b. power means for rotating said shaft in either direction, c. a valve control member fixedly mounted on said shaft and movable therewith, d. said valve control member including a cam drum fixedly mounted on said shaft, e. a plurality of screw members arranged in a row along a substantial portion of the periphery of said cam drum, f. said screw members extending through the cam drum periphery to varying extents, whereby the inner ends of the screw members form a camming surface, g. said valve control member further including a cam roller, h. said cam roller being provided with an elongated vertical slot through which said shaft extends, i. the periphery of said cam roller being in selective engagement with a portion of the camming surface of said cam drum, j. a cam follower pending from said cam roller into actuating engagement with the valve, and k. means for automatically energizing said power means in response to variations in boiler steam pressure to rotate said shaft in either direction, l. whereby the point of contact of said camming roller is changed, thereby effecting vertical movement of said cam roller and cam follower to change the rate of flow of fuel through the valve.
 5. A fire control assembly for regulating the flow of fuel and an atomizing agent through valves to a burner, the assembly including: a. a rotatable shaft, b. power means for rotating said shaft, c. means for actuating said power means, d. a pair of like valve control members fixedly mounted on said rotatable shaft, e. each of said valve control members including cam members providing a camming surface fixedly mounted on said rotatable shaft, f. means engageable with said camming surface of each control member in operative engagement with the valves for regulating the flow of fuel and atomizing agent through the valve, g. said means engageable with each of said camming surfaces including a cam roller, h. said cam roller having a vertical elongated slot through which said rotatable shaft extends, said cam roller being in selective engagement with portions of said cam members upon rotation of said shaft, j. whereby the valves are opened and closed.
 6. The fIre control assembly of claim 5, wherein a. said cam member includes a cam drum fixedly mounted on said rotatable shaft b. a plurality of camming members extending through the periphery of said cam drum a predetermined extent c. the inner ends of said camming members forming a camming surface, d. said camming surface being in engagement with said cam roller.
 7. The fire control assembly of claim 6, wherein a. said camming members comprise screws threaded through said cam drum and adjustable with respect thereto.
 8. The fire control assembly of claim 7, wherein a. said camming members extend through an arc of at least 180* on said cam drum surface.
 9. A fire control assembly for regulating the flow of fuel and an atomizing agent through valves to a burner the assembly including a. a rotatable shaft, b. power means for rotating said shaft, c. a pair of synchronously operating valve control members mounted on said shaft, and movable therewith, d. each of said valve control members including a cam drum fixedly mounted on said shaft, e. a plurality of screw members arranged in a row along a substantial portion of the periphery of said cam drum, f. said screw members exending through the cam drum periphery to varying extents, whereby the inner ends of the screw members form a camming surface, g. each of said valve control members further including a cam roller, h. said cam roller being provided with an elongated vertical slot through which said shaft extends, i. the periphery of said cam roller being in selective engagement with a portion of the camming surface of said cam drum, j. a cam follower pending from said cam roller into actuating engagement with the valve, and k. means for automatically energizing said power means in response to variations in boiler steam pressure to rotate said in either direction, l. whereby the point of contact of said camming surface of each valve control member with the cam roller is changed, thereby effecting vertical movement of said cam roller and cam follower to change the rate of flow of fuel through the valve.
 10. A fire control assembly for regulating the flow of fuel and an atomizing agent through valves to a burner, the assembly including: a. a rotatable shaft, b. power means for rotating said shaft, c. means for actuating said power means, d. a valve control member fixedly mounted on said shaft and rotatable therewith, e. said rotatable valve control member including means providing a camming surface, and f. means between said camming surface and one of the valves for opening and closing the valve for regulating the flow through the valve upon rotation of said shaft, g. said means between said camming surface and valve including a cam roller, h. a cam follower pending from said cam roller into actuating engagement with the valve. 